Low pressure carburising (LPC)
LPC is a case hardening process carried out in a vacuum furnace using hydrocarbon gases at very low pressure and elevated temperatures to obtain a hardened surface layer of tempered martensite and a tough core. The treatment is used to increase the wear resistance and fatigue life of components.
The pitch to root ratio of the carburised layer (case depths) in gears is almost 1:1 (uniform).
High hardness below the surface compared to conventionally carburised parts.
Faster cycle times.
Parts can be carburised between 930°C and 1000°C (1700° and 1830°F).
Penetration of carbon in deep blind holes resulting in uniform hardness on the entire profile.
Carburising of small holes and blind holes.
Avoidance of part cleaning after the heat treatment due to high pressure gas quenching (dry quench).
Reduction of dimensional alterations by temperature-independent heat transfer during high pressure gas quenching.
Enhanced mechanical properties – elimination of inter-granular oxidation layer, improved fatigue properties.
Dimensional control – low distortion, predictable and repeatable
Reduced manufacturing steps such as post grinding, cleaning and inspection
Enhanced cleanliness of products
Precise control of case depth, microstructure and hardness
Better case depth uniformity for complex shapes. Case depth uniformity can be maintained within ±0.002” in most cases.
Application & materials
Typical applications of LPC include gears, shafts, axles, nozzles, injectors, spindles etc.